Abstract: Under the conditions of high pressure and large flow, the throttle element of the control valve has problems such as unstable decompression and speed control and serious cavitation erosion. A new type of ant-hole throttling element(ATE) is proposed. Based on the CFD simulation analysis, the variation laws of the inter-stage pressure, velocity and vapor phase volume fraction of the throttling element under different pressure reduction stages and different pressure levels were studied in detail. The critical cavitation pressure values of different depressurization stages are obtained and compared with the flow field characteristics of conventional labyrinth throttling elements. An experimental system is built to measure the inter-stage pressure and flow of throttling elements with different pressure reduction stages under different valve port pressure drop conditions and compared with the simulation results. The results show that：Compared with the labyrinth type throttling structure, the ant-hole type throttling element is more stable in decompression and speed control, and has better linearity. The cavitation of the ATE mainly occurs in the last stage, and there is a linear relationship between the pressure drop at the valve port and the number of pressure reduction stages. Based on the obtained expression of the linear relationship between the pressure drop at the valve port and the number of pressure reduction stages, theoretical guidance is provided for designing the optimal combination of pressure reduction levels and pressure reduction stages. Thereby avoiding the occurrence of cavitation and improving the service life of the control valve. The experimental data is in good agreement with the simulation data, which verifies the accuracy of the simulation model.

Key words: ant nest type throttling element, cavitation, decompression and speed control, flow field simulation calculation